What do helium and hydrogen have to do with the Big Bang?

Answer 1

The observed proportions and distribution of hydrogen and helium are consistent with what would be expected if the Big Bang model were accurate. The Big Bang model describes how, from the cooling universe, the simplest atoms would have condensed from the hot broth of fundamental particles most easily: a proton and an electron, forming hydrogen. Far fewer particles would have combined to form helium, requiring two protons and one or two neutrons. The likelihood of spontaneous condensation of elements then decreases rapidly with the complexity of the element, so very few heavier elements could have formed that way. Initially, almost all of the visible matter in the universe consisted of hydrogen and helium, according to the Big Bang model. Heavier elements would have been formed through nucleosynthesis in the cores of stars and supernovae. When we look at the proportions and distribution of the elements, especially hydrogen and helium, this is indeed what we find.

Answer 2

I'm going to presume the question you're asking is, "Does the ratio of hydrogen-1 to helium to deuterium to lithium support the Big Bang Theory?"

The answer is yes -- very strongly. The ratios of these isotopes to each other -- which appears to be about the same in all parts of our Universe -- are pretty much as predicted by the Big Bang. All other hypotheses are reduced to saying, "I have no idea why these isotopes are the ratios they are -- they just ARE that way, and I have no way to explain it."

Answer 3

The Big Bang produced hydrogen, helium, and trace amounts of lithium once the universe was cool enough for atoms to form.